1. Field of the Invention
The present invention relates to an information processing method, printing apparatus, and computer-readable medium for generating print data in a printing apparatus which forms an image on a printing medium with a plurality of types of printing materials.
2. Description of the Related Art
Recently, various types of printing apparatuses have been proposed as information output apparatuses for a word processor, personal computer, facsimile apparatus, and the like. The printing apparatus prints desired information such as text and images on a sheet-like printing medium such as paper or a film. Of these printing apparatuses, a printing apparatus which forms text and images on a printing medium by applying a printing material to the printing medium has become commercially available. A typical example of this printing apparatus is an inkjet printing apparatus. These days, the performance of inkjet printing apparatuses has been improved to print not only text but also color images.
As the image quality of color inkjet printing apparatuses has improved, so-called photo printing has become popular for outputting digital images using the color inkjet printing apparatuses. As photo printing has prevailed, preservation of printouts becomes important.
Conventionally, dye ink has been mainly used as a printing material in the inkjet printing apparatus. However, the preservation properties of dye ink are poor, so the color inkjet printing apparatus sometimes uses pigment ink, which are known to have excellent preservation properties.
Some of the above-described inkjet printing apparatuses use a plurality of types of inks, and reproduce multi-color, multi-tone images by forming a plurality of types of ink dots on top of each other on a printing medium, as disclosed in Japanese Patent Laid-Open Nos. 2003-54016 and 6-171111.
When the color is reproduced by discharging ink onto a printing medium, the reproduced color and glossiness sometimes change depending on the order in which a plurality of types of inks are superposed. As the color reproduction range is wider (colors in a wider range can be reproduced), a higher image quality can be achieved. According to a technique disclosed in Japanese Patent Laid-Open No. 2004-155181, color reproduction ranges when superposing inks in all orders are measured in advance, and the ink discharge order is controlled in accordance with the measurement results.
Japanese Patent Laid-Open No. 2005-193463 discloses a technique of suppressing a decrease in glossiness by printing with inks in an order in which an ink other than one having the highest density or an ink other than one having the lowest glossiness is superposed finally.
In practice, however, no conventional technique has made a close examination of the relationship between a concrete ink superposition order and the color reproduction range.
According to a method of measuring color gamuts by printing in all color orders in advance, as disclosed in Japanese Patent Laid-Open No. 2004-155181, the number of processes abruptly increases as the number of colors used, the number of printing media, and the number of print modes increase. Hence, this method is not practical in multi-color printers.